It is well known in the art of manufacturing concrete pipe and other similar structures, such as manholes, box sections, catch basins, septic tanks and the like (hereinafter simply “product” or “products”), that a reinforcing wire cage is provided as reinforcement to produce a product of the required strength. In order to produce a quality concrete product, the reinforcing cage must be positioned within the concrete forms used to produce the product so that the cage will be a predetermined distance from the inside and outside walls of the finished product. Since the cage will be subjected to various forces during the product manufacturing process, it is important that the cage be properly positioned from the walls of the forms and that the required distance from the forms be maintained throughout the casting process. In order to accomplish the proper spacing, there are commonly provided spacing elements, called spacers, which can be fastened to the cage to space it from and maintain it the proper distance from the form walls.
In the casting process, an inner core and an outer jacket create an annular space that receives the wire cage. To properly position the wire cage, numerous spacers are placed on the wire cage. The spacers must be designed to resist the forces exerted on them during the casting process. If the spacers fall off during the casting process, the cage can move out of position, which can result in the finished product not meeting the product specifications. The two commonly used methods of producing concrete products create different forces on a reinforcing cage and thus upon the spacers installed on the wire cage. One of the common casting methods is the vibration process which involves lowering the jacket over the core after the wire cage is in place. Unless the spacers used are capable of resisting the downward axial forces applied as the jacket is lowered in place, the spacers can be dislodged or distorted. Another commonly used method of producing concrete products is the packer head process. In this process, the spacers installed on the wire cage must be capable of resisting not only the axial forces that occur, but also the forces upon the spacers as the cage twists during rotation of the packer head.
There are known and used a number of different spacers which have been designed in an attempt to resist all of the forces exerted upon the spacers during the casting process. Many spacers are formed from spring steel with an open hook at each end to provide for attaching the spacer to the reinforcing cage. Between the attaching hooks of the spacer there is typically formed a spacing nose to maintain the wire cage the proper distance from the forms. These steel spacers work well in most instances, but occasionally some of the spacers can become dislodged from the cage. Also, because of some new state requirements, steel spacers are no longer approved for use because the exposed metal can lead to rusting and result in rust spots and corrosion.
Some attempts have been made to improve the design and lower the cost of spacers by making them from plastic in the shape of a wheel with spokes and a central ring that engages a horizontal wire on the wire cage. These plastic spacers require no special tools to install. However, with known designs of this type, the forces exerted on them during the casting process may twist the spaces and cause some of them to fall off the wire cage.
There is therefore a need for an improved spacer useable in any of the known casting processes and designed so as to be capable of resisting forces in all directions so that the spacer cannot become dislodged and produce voids or other defects in the finished product. There is a further need for an inexpensive spacer that will permit easy and quick installation without the use of any special tools.